demonstrations:liquid_nitrogen_freezing_fruit

Liquid Nitrogen Freezing Fruit

Materials: ★★★ Requires materials not commonly found in school laboratories
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★★ Only to be attempted with adequate safety procedures and trained staff

Categories: Liquid Nitrogen

Alternative titles: Cryogenic Fruit Shattering

Summary

When fruit such as a strawberry or berry is submerged in liquid nitrogen, the water inside its cells freezes almost instantly. This rapid freezing makes the fruit rigid and brittle, so when struck with a hammer or mallet, it shatters instead of squishing.

Procedure

  1. Put on safety glasses and cryogenic gloves.
  2. Place a piece of fruit (e.g., strawberry, blueberry, or grape) into a container of liquid nitrogen.
  3. Leave it submerged for several minutes until frozen solid.
  4. Using tongs, remove the fruit and place it on a sturdy surface.
  5. Strike the fruit with a hammer or mallet to demonstrate its brittle, shattered texture.
  6. (Optional) Record the demonstration with a high-speed camera to capture the shattering effect in detail.

LIQUID NITROGEN VS FRUIT | Brothers Do Science: In The Lab - Oli White:


Cryoshattering Fruit - ChefSteps:


Variations

  • Try different types of fruit (apple slices, banana pieces, or grapes) to compare textures when frozen.
  • Use leafy vegetables (like lettuce or spinach) to show how they crumble when frozen.
  • Compare the crushing of frozen fruit to unfrozen fruit to highlight the difference.

Safety Precautions

  • Safety glasses required.
  • Wear cryogenic gloves when handling liquid nitrogen and frozen fruit.
  • Use tongs to remove fruit from liquid nitrogen - never touch it directly.
  • Only strike fruit on a stable, non-breakable surface.
  • Do not eat fruit until fully warmed to room temperature.
  • Ensure liquid nitrogen is handled only in a well-ventilated area.

Questions to Consider

  • Why does the fruit shatter instead of squish when frozen with liquid nitrogen?
  • What happens to the water inside the fruit’s cells during rapid freezing?
  • How does this relate to why frozen fruits at home sometimes feel mushy when thawed?
  • How do industrial freeze-drying or cryopreservation techniques use similar principles?
  • What does this experiment teach us about states of matter and the effects of temperature on materials?